One world government refers to the idea of a central government whose authority extends across the entirety of this planet. The idea is generally that the many countries of the world would join together in a federation under one central government, similar to how federal states such as the United States, Australia, Canada or Switzerland were formed.

The most common proponents of this idea adhere to "liberal internationalism." Commonly, they believe in a strengthened United Nations evolving into a world government. It is frequently suggested that the UN be supplemented with a directly elected parliamentary assembly, to give the UN authority independent of member states. They support international law as paramount over national law, and see it evolving into a single global legal system, with individual citizens having direct access to international courts with the power to overrule national legislation.

Another viewpoint believes that world government must be preceded by continental or regional government. This viewpoint supports the strengthening of the European Union, and the duplication of the EU model in other regions of the world. It looks to the EU as one of the most advanced states of supranational integration in the world today. Once the world has been organised into regional or continental governments, then world government can be established as a federation of these regional governments.

There are other viewpoints which expect the formation of a world government, but do not look forward to the idea. Many premillennialistChristians believe that, at the end of the world, a one world government will be established under the rule of the Antichrist. Whereas liberal internationalists see one world government as a good thing, and see the early signs of its development as a positive, many premillenialists see those early signs as evidence that we are approaching the End Times. The idea of one world government is frequently linked with that of one world religion.

Some have viewed one world government as the outcome of world conquest (by an individual such as Hitler) or the inevitable triumph of a particular political project (e.g. a global commie revolution), or, simple imperialism.

A provisional "World Government of World Citizens" was declared on September 4th, 1953 in Ellsworth, ME by self-proclaimed world citizen Garry Davis. Its administrative agency, the World Service Authority (WSA), was founded next year, and is active to this day, mainly in issuing documents, such as World Citizen Registration Cards, World Passports, World ID Cards and World Marriage Certificates. Six countries gave official recognition to the World Passport at one stage or another.[1] According to the WSA's archives, as of 2010, 180 countries stamped the World Passport or issued a visa on it at least once.[2] Several nations have stated in their consular manuals they do not recognize WSA passports.[3] It should be noted, however, that those are consular guidelines and not laws; thus the final decision remains with the particular official.

Another viewpoint, as a response to both realist and liberal internationalist approaches, is that if a one world government does come into fruition, it ought to be based on the principle of subsidiarity: wherein individual countries and regional blocs retain at least some sovereignty while delegating certain powers over to a reformed United Nations, thus rendering its actual power strictly limited but real enough to function. Proponents tend to present such proposals as a moderate option and an answer to concerns over self-determination and what form said global government ought to take.

Realist and "communitarian" approaches to international relations see liberal internationalist proposals for one world government as wishful thinking, which are centuries away from fruition, if they ever will be. Critiques of the concept, including those from other liberals posit that such a global state would be either unwieldy, unaccountable or undesirable (if not impossible) for various reasons. It also brings up other questions, such as whether a world government is necessary at all or if it would really be in everyone's interests.[4]

World governments are common in science fiction novels involving aliens, often formed as a response to first contact. The suggestion is that only an outside threat could truly bring about a world government. Fictional world governments fall into a wide variety of categories.

Some of the more crankconspiracy theorists, such as David Icke, believe that shapeshifting alien reptoids have infiltrated human society and are scheming to take over the world.